Cold Blast Coming

Our coolest temperatures so far of the cold season are right around the corner.  Next week, the setup is favorable for temperatures to fall.

Here's what we have.  The jet stream looks to kink itself early next week, becoming oriented north to south.  This push will open the door up to a cold air flow in from Canada by late Monday into Tuesday.

In the winter, to get the coldest temperatures at night, there's three ingredients you need.  Clear sky, Light/no wind, Fresh snow.  Locally we're lacking the snow cover.  A weak disturbance due Monday may try to bring a little light snow to the area but not enough to influence temperatures.  So we're left looking at the other two, clear sky and very little to no wind.  Those two, we do have.

Below shows an area of high pressure moving into the Dakotas from Canada early Tuesday.  This should be strong enough to keep significant cloud cover away.  To the east of the high, winds are oriented from the north, letting colder air in.  But the closer you get to the center of the high, the lighter the winds become.  Without wind, the lowest levels of the atmosphere doesn't mix.  Without the mixing, radiational cooling of the earth is pronounced.  This process is called Boundary Layer Decoupling.  Therefore, lower temperatures are expected. 

As shown in the image above, temperatures by this particular computer model are expected to drop close to 15°F on Tuesday morning.  In case you're wondering, the record low is -1, set back in 1986, so we aren't close to record range just yet.

So far this season, 24° has been our coolest mark in Rochester, on October 22nd and 25th.

Click here for the Storm Tracker 6 Forecast for the next week ahead.

Storm Tracker 6 Chief Meteorologist
Chris Kuball